Hydroponics Application Note

Benefits of the IQ ISFET handheld pH meter systems:

	Rugged- waterproof and no glass to break
	Portable- can go anywhere to monitor a system
	Easy to use- simple calibration which is retained after shutoff
	Easy to clean- with toothbrush and detergent, then store dry
	Long-lasting- 15,000-20,000 tests typically

When the pH of hydroponic systems is not at the right level, a plant will lose its ability to absorb the essential nutrients necessary for healthy and successful growth. The IQ ISFET pH meters monitor the pH levels of a system with accuracy and reliability.

Hydroponics is a system that utilizes nutrient-enriched water instead of soil. Hydroponics' major advance is being able to control a plant’s environment by delivering the nutrients it needs directly to its root system several times a day. Therefore, the plant uses less energy searching for nutrients and more energy growing faster and producing more.

Each plant has a specific pH level which allows it to achieve maximum growth, but generally, most plants grow well in a slightly acidic solution in the pH range of 5.8 to 6.8. However, plants can survive in a range of 5.0 to 7.5. Daily pH measurements give one better control of their system and a familiarization with the relationship between nutrient concentration and pH levels.

The following table shows approximate pH values and ranges for a variety of fruits and vegetables:

pH Values for Different Hydroponic Crops
(from Hydroponic Food Production by Howard M. Resh, Woodbridge Press, 1987)

If the pH is too high, plants suffer from a lack of iron, zinc, manganese, copper and boron. If the pH is too low, plants lack phosphoric acid, calcium, and magnesium. At lower pH ranges, diseases can thrive. Normally, plants tend to take up more acidic elements, causing pH levels to increase. The addition of acid is common in systems to lower pH. Phosphoric acid and nitric acid are the most commonly used adjusters. In cases that require an increase in pH levels, potassium hydroxide is an alkali used most often. For smaller growers, ready-mixed pH-up or –down solutions are available at most supply stores.

Recalculating hydroponic systems need to be accurately tested and adjusted as the growing plants feed on select salts in the nutrient solution. When these salts are removed, the concentration of the nutrient solution deteriorates and changes the pH. The nutrients will eventually be used up, leaving a solution made up only of water and unusable salts. So for maximum growth, the nutrients must be kept at their optimal concentration. The solution can be adjusted by adding water to decrease the concentration or nutrient salts to increase the concentration. The pH can also be adjusted with pH buffers.

If the pH levels are continuously dropping, there are a few factors that could be the cause. The pH meter might need to be checked or recalibrated. Check the root systems for possible root death caused by harmful conditions in the mix. Also, the initial nutrient solution may not have had a good buffering capacity, making it less resistant to pH changes.

When first starting out, be sure to get a pH reading of the initial water source. This will give an indication of the pH starting point and any adjusting that will need to be made. Most water supplies, including rainwater, are usually problem-free in or are easily adjusted with acids or alkalis before one begins growing.

For best results in a hydroponic system, we recommend either the IQ125 miniLab professional pocket-sized pH meter or one of our handheld ISFET pH meters. These meters feature durable silicon chip sensors, which eliminate the risk of traditional glass bulb sensors. The sensors are stored dry and require no maintenance. The meters are water-resistant with built-in temperature compensation and a long battery life. Error messages alert you to possible problems in advance. These meters are easy to use and maintain a high degree of accuracy to successfully monitor the system. Click here to view these meters.